Rated 4 out of 5 stars

Great functionality, great enhancement. The default design, however, does not integrate very nicely into the default Thunderbird UI. But thanks to the extensive options, I was able to tweak its visual appearance to have a perfect fit:

http://i.imgur.com/NTQ5n3J.png

Thank you for maintaining this extension!

This review is for a previous version of the add-on (3.14.1). 

nice one!

and well done on finding a visual style you find pleasing von your particular operating system / mail application :-) feel free to suggest another theme but bear in mind that the look of the host program (I support three, Thunderbird , SeaMonkey and Postbox) is very largely dependant on the skin your current operating system uses [so you already have 9 different looks by just using one version of each OS with default style. On Windows alone you can have a multitude of looks dependant on the skin you use - I personally use Windowblinds to further vary the look adn full themes on Thunderbird to modify the look even more - I highly recommend Nautipolis] so it is practically impossible to support all different looks without making this a full time job. Also I do not currently own a Macintosh so I can't even guess how my tabs are going to look on there.

My advice for a most native look would be to use the theme "native tabs" (I designed the QuickFolders with tabs in mind, even before Thunderbird supported tabs) or toolbarbuttons. I personally prefer something more colorful, hence "Flat Tabs" is the default.

I hope you will find Quickfolders a useful tool in the future,and let me remark that although the user interface is a big part of it, the main focus of this extension is actually about productivity. I am still learning myself what can be done with it, and I am working on the development for 5 years now. Make sure to reach out to me for the latest prereleases and to test drive the newest features I have come up with.